Device adapted to show whether an electric incandescent lamp has been in use.



S. KLEIN. DEVICE ADAPTED TO sHow WHETHER AN ELECTRIC INGANDESGENT LAMP HAS BEEN IN USE.

APPLICATION FILED MAR. 17, 1910. RENEWED MAY 1, 1913.

1,077,479, Patented Nov. 4, 1913.

- \NVENTOR. 5mm Kuzm,

STATES PATENT OFFICE.

SIMON KLEIN, OF BERLIN, GERMANY, ASSIGNOR 'IO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

DEVICE ADAPTED TO SHOW WHETHER AN ELECTRIC INCANDESCENT LAMP HAS BEEN IN USE.

Patented Nov. 4, 1913.

Application filed. March 17, 1910, Serial No. 550,059. Renewed May 1, 1913. Serial No. 764,936.

To all whom it may concern:

Be it known that I, SIMON KLniN, engi' ricer-chemist, a citizen of Germany, residing at No. 126 Miillerstrasse, in the city of Berlin, German Empire, have invented a new and useful Device Adapted to Show Whether an Electric Incandescent Lamp Has Been in Use; and I do hereby declare the following to be a full, clear, and exact description of the same.

The invention relates to an attachment for electric incandescent lamps, adapted to show whether such a lump has been used, and to enable the time of its use to be controlled.

It is universally known that lamps having metal filaments are relatively very expensive and easily broken. For this reason, it is usual for the manufacturer to replace such lamps as become defective during the transport or when first put into use. Herefofore, only a very long use could be ascertained by examining the condition of the filament, and it frequently happens that the purchaser claims new lamps for those which have been in use for a considerable time.

For manufacturers of electric incandescent lamps, it is, therefore, of great importance to provide means which will clearly show whether a lamp has been put into use.

According to my invention,I provide such a device, which, when the circuit of the lamp is closed, that is, when the lamp is burning, is so modified by physical, chemical or other actiomthat the fact of the lamp having been used can be discerned. For this purpose, any light sensitive color may be used. I may use a paper which has been rendered sensitive to light, or I may employ cotton or felt steeped in such light sensitive coloring material. This light sensitized material is introduced into the seal of the lamp in the hollow space left in the process of manufacturing the lamp. For photographic purposes there are manufactured a number of light sensitive colors, and these may be used with greater or less success. I have used with complete success a color material which is sold in the trade under the name Tosulrot. I am unable to give the chemical composition of this material, as it is kept by the manufacturers as a trade secret.

In the accompanying drawings, I illustrate one manner of using my invention.

Figure 1 shows, in elevation, a metal filament lamp; Fig. 2 is a fragment, showing a longitudinal section through the glass seal or base; and Fig. 3 is a cross-section, on the line AB, of Fig. 2.

The lamp shown in Fig. l is constructed in the well-known manner, and-comprises a small glass tube or base a having an outwardly-flaring flange b, which is molten on to or fused to the lower end of the bulb d. Conductors g, '9, pass through the upper flattened and compressed end 0, of the seal a, and that end supports a carrier f, of glass, for the filaments, k. Within the hollow space, it, of base, a, there is a material, 6, for example, wool or felt steeped in a material such as tosulrot which, under the action of light from the filaments it changes its color or tint.

I have found it to be ofspecial advantage to provide some substance of a color sensitive to light in the glass foot of the incandescent lamp, and the dye used should preferably be of a character adapted to the special physical and chemical properties of the light emitted by a metal filament. Under the influence of the light of the lamp, the dye will pass through various stages, showing the time the lamp has been in use. The provision of such a sensitivesubstance in the foot of a lamp is of specialadvantage, because at this place it is protected more or less against day-light, and, moreover, the day-light must pass through the wall of a and also through the wall of d, before it arrives at the dyed substance, While the lamp light, which moreover is richer in ultra violet rays, has only to pass through one thickness, that of a. Moreover, the color with which material 2' is steeped is so chosen that it is less sensitive to daylight than to the light emitted from the incandescent metallic filament. The fading or change in the color of the substance, as experiments have shown, will enable the time the lamp has been used to be ascertained. For the purpose last mentioned, it is of advantage to provide several materials of different colors or of colors having different degrees of sensitiveness, which, according to the time the light has acted on the same, passthrough various stages. A It should be mentioned that this device can. be adopted not only to show whether incandescent lamps have been .in use, "forwhich purpose however 1t is of great importance, but also for other apparatus, in which the electric current produces light.

What I claim and desire to secure by LettersPatent of the United States is: I

1. The combination, with an incandescent lamp, of a device sealed thereto and-adapted to show whether said lamp hasbeen used,

adapted, by chang substantially as set forth.

2. The combination, with an incandescent lamp, of a substance sensitive to light and ing its appearance under 4. The combination, with an incandescent lamp, of a porous substance has been used, substantially as set.

U d ed-in a color sensitiveto light, substantiall as and for thePurpose set forth. I

5. The combination, with an incandescent lamp,-of a body sensitive to light and provided in the foot of said lamp, substantially as'and for the purpose set forth. 6; An article of manufacture comprising an incandescent lamp and means permanently attached thereto and adapted to be affected by the influence of the light of the 1am; to 'showwhether the lamp has been use. r

7. An article of manufacture comprising, an incandescent lamp having a base-tube, a substance sensitive to light in said tube, and a lamp socket sealing said tube. In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

SIMON KLEIN.

Witnesses:

HENRY HAsPEn, WOLDEMAR HAUr'r. 

